1. Field of the Invention
This invention relates to magnetic particle processing, and, more particularly, a system for inverse magnetic particle processing.
2. Discussion of the Art
Automated analyzers are well-known in the field of clinical chemistry and in the field of immunochemistry. Representative examples of such automated analyzers include, but are not limited to, PRISM® analyzers, AxSYM® analyzers, ARCHITECT® analyzers, all of which are commercially available from Abbott Laboratories, Cobas® 6000, commercially available from Roche Diagnostics, Advia, commercially available from Siemens AG, Dimension Vista, commercially available from Dade Behring Inc., Unicel® DxC600i, commercially available from Beckman Coulter Inc., and VITROS, commercially available from Ortho-Clinical Diagnostics. Each of these analyzers suffers from various shortcomings, some more than others. Some of the shortcomings encountered by more than one of these automated analyzers include the use of large volumes of sample, the use of large volumes of reagents, the generation of large volumes of liquid waste, and high costs. Some of the aforementioned automated analyzers require a great deal of maintenance, both scheduled and unscheduled. In addition, some of the aforementioned automated analyzers have scheduling protocols for assays that cannot be varied, i.e., the assay scheduling protocols are fixed, which limits such features as throughput.
Users of automated clinical analyzers desire to automate as many functions as possible. In the area of automated immunoassays, some of which require separation of reaction products from a reaction mixture in a reaction vessel, certain types of subsystems are necessary for separating a solid magnetic substrate from the liquid contents of a reaction vessel. These liquid contents can be unbound sample, unbound conjugate, wash buffer, a pre-trigger solution. Some automated immunoassay analyzers do not have the necessary versatility that would enable them to be used in systems that are designed to allow seamless integration with clinical chemistry analyzers. For example, magnetic separation of solid magnetic substrate from the liquid contents of a reaction vessel is difficult to integrate with clinical chemistry assays because of the need to use external magnets, washing mechanisms, in-track vortexers, inflexible process paths, and instantaneous dispensing of liquids at certain key points of immunoassay protocols.
Commercially available subsystems for separating a solid magnetic substrate from the liquid contents of a reaction vessel that do not have (a) an incubation capability integrated with such separating capability, (b) an automated interface for loading reaction vessels, and (c) radio frequency reading of radio frequency identification tags attached to reaction vessels are difficult to operate efficiently.
Magnetic separation of a solid magnetic substrate from the liquid contents of a reaction vessel can be carried out by a method known as inverse magnetic particle processing. The operating principle of inverse magnetic particle processing technology, commonly referred to as MPP, involves moving magnetic particles from one micro-well to another micro-well, e.g., from a micro-well in a given row and column of a micro-well plate to a micro-well in the same row and in another column of the micro-well plate, at least one micro-well in the micro-well plate containing reagent(s) required for the immunoassay, rather than moving liquids from one micro-well to another micro-well. This principle stands in contrast to the external magnet method, which is used in such automated analyzers as the ARCHITECT® analyzer, commercially available from Abbott Laboratories. According to inverse magnetic particle processing technology, magnetic particles are transferred with the aid of the magnetic rods covered with disposable, specially designed plastic tip combs.
Magnetic particle processors are commercially available under the trademarks KingFisher™ and KingFisher™ 96 from Thermo Fisher Scientific, Inc., Waltham, Mass. These magnetic particle processors are described, for example, in U.S. application Ser. No. 11/923,828, filed Oct. 25, 2007, and entitled METHOD OF PERFORMING ULTRA-SENSITIVE IMMUNOASSAYS, incorporated herein by reference.
Customers desire automated assays and throughput for these assays that are tailored to their requirements. However, subsystems for magnetic separation and mixing that are currently commercially available cannot be reconfigured and are not designed to have features that allow customization. In addition, customers desire to incorporate new assays into their automated analyzers without the need for changing the automated analyzers. Subsystems for magnetic separation and mixing are not designed to have features that support new assay protocols. Therefore, it would be desirable to develop a magnetic particle processor that would be sufficiently flexible to enable users of the magnetic particle processor to reconfigure the magnetic particle processor and to customize the magnetic particle processor for desired operations, so that new assays can be incorporated into an automated analyzer without the need for changing one magnetic particle processor for another.